Feed a cold, starve a fever

Some scholars believe that the interpretation of the adage is, "If you stuff a cold, you will have a fever to starve". Others interpret it literally. Nobody knows for certain where the phrase came from.[1] The first documented use of the adage was in John Withals 1574 book, A shorte dictionarie most profitable for yong beginners. In the book Withals includes the phrase, "Fasting is a great remedie of feuer".[2]

A 1942 paper published by The Johns Hopkins University Press, Feed a cold, starve a fever was determined to be justified according to medical knowledge.[1][3]

In BBC Science Focus an article discussed the positive effects of a ketogenic diet on illness. But they also state that there "may be a thread of scientific truth to the old adage ‘feed a cold, starve a fever".[4] A 2002 study in Holland learned that eating activates an immune response which kills a cold virus, but fasting provokes an immune system response which attacks bacterial infections which are responsible for many fevers.[5]

A 2007 New York Times article concluded, "There is little scientific evidence behind the notion of starving a cold and feeding a fever, or vice versa."[6] A 2017 CNN article suggested that starving is not a good idea. CNN quoted pediatric infectious disease expert Dr. Jon S. Abramson, as saying. "Feed a cold, feed a fever. Nurture your body, and never starve it". They also quoted Emory University internist Dr. Sharon Horesh Bergquist who agreed but also advised. "When you’re sick, drink more than you think you need".[7]

When a person is sick or has infection in their body, white blood cells release cytokines to fight infection. The Cytokines affect the hypothalamus part of the brain which may arrest hunger resulting in a loss of appetite.[8] In 2002 scientists in Holland studied the issue by setting up small-scale tests which monitored consumption among participants. They discovered that consuming different food or liquid activates different immune cells.[9] In the study researchers determined that certain foods might be given to sick patients in order to stimulate the correct immune system response in the patient.[5] Some scientists have said the results of the Dutch study little merit because it was small-scale, and the results have not been replicated.[6]

Professor Ruslan Medzhitov, of the Yale School of Medicine states, not eating is a common behavior during an illness. Medzhitov has discussed experiments on mice where mice that were infected with listeria bacteria, when they were made to eat, died. The animals stopped eating naturally, eventually recovered. Sugar (glucose) was determined to be detrimental: mice survived after being fed protein and fats but no glucose. Another study of mice infected with the flu virus showed that the infected mice survived when fed glucose. The flu infected mice died when they were not given food.[10][11]

Dr. Sharon Bergquist of Emory University suggests that liquids are more important for recovery than eating. She said, if a cold or fever has altered a person's appetite they should not force feed. But a sick body needs nutrition in order to assist the immune system.[12]